I tried the keto diet that’s sweeping Silicon Valley with help from a gadget that tracks your progress

Ketogenic dieting has become a favorite pastime of Silicon Valley techies who want to hack their bodies to improve energy levels and performance. The regimen involves eating foods that are high in fat and some protein, while keeping carbohydrates to a minimum.

The goal of ketogenic diets is to get body to a state calld “ketosis,” which requires keeping carbohydrates to less than five percent of daily caloric intake. Once that happens, the body burns stored fats instead of recently eaten carbs, resulting in a buildup of acids called ketones within the body.

Some critics say “keto” is just another fad diet, like Atkins or Whole30, but others rave about the benefits of being in ketosis, ranging from weight loss to increased energy.

Ketones can actually be measured in the blood, the urine and the breath, which is how many people on the diet figure out if their carb restriction is having an impact. But measuring it through the blood or urine is a bit much for some.

So Keyto, a new start-up in the space, aims to make it easier for people on ketogenic diets to track their body’s transition into ketosis by simply blowing into a device. It was founded by Ethan Weiss, a cardiologist at UC San Francisco, and former Weight Watchers vice president Ray Wu.

Weiss offered me the opportunity to join the beta program and get early access to the device, as I’ve long been curious about the keto diet. I’d heard from advocates of the diet, including Weiss, that it can help with afternoon energy slumps, which sounded appealing. I often feel tired in the middle of the day, and rely on caffeine or a sugary snack to keep going.

Weiss provided me with a device that resembles bright orange breathalyzer to assess if I’m in ketosis. I also downloaded the Keyto app, which I used to search for foods to find out if they’re keto-friendly or not.

CNBC | Adam Isaak

The Keyto device tracks your state of ketosis when you breathe into it.

Through that process, I quickly learned that I’d be spending a few weeks snacking on smoked salmon, scrambled eggs, macadamia nuts, cheese and avocado. I’d need to cut out foods I love like chocolate and dried fruit.

My two-week experiment

To use the Keyto device, you blow into it until you get to the bottom of your breath. Then you get a score from 1 to 10 that tells you how deep you are into ketosis.

The first time I breathed into the device, I got a 2. By the fourth day, I blew a 6, which proved to be my highest score. That meant I was in medium levels of ketosis. I hovered around there for most of my two-week experiment.

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Blowing into the Keyto device

On the plus side, the regimen helped me notice what I was eating, and I started to move away from processed foods, and moderate my intake of sugary sauces, sweetened yogurt, fruit, beans and certain starchy vegetables. I also started looking at nutritional labels in the grocery store to check sugar levels, and noticed that some of the foods I thought were healthy were actually jam-packed with sugar. Culprits included many varieties of yogurt, snack bars, and salad dressings.

I also noticed that I cooked at home more rather than picking up delivery or eating out, because I couldn’t trust restaurants to offer sufficiently low-carb options.

It wasn’t all smooth sailing. I had a few rough days where my body was weaning off sugar. I felt pretty terrible on days three and four, with symptoms that resembled a low-grade cold, but I had fully bounced back by the end of the first week. In the second week, I stopped getting afternoon energy slumps and woke up less hungry than usual. I also had energy to get back to the gym, which helped me adjust to feeling a bit more normal.

I also felt less social in that first week, as I hadn’t figured out which restaurants and cuisines were better suited to those on keto. So I tended to eat at home instead, although I could still meet people for drinks — the diet still let me drink a glass of wine, or my keto go-to: gin and soda. (As a Brit, I typically prefer a G&T, but tonic water is packed with sugar.)

Adam Isaak | CNBC

I also spoke to people who had tried out keto for longer, like health-tech entrepreneur Robbie Cape, who did lose weight but saw their cholesterol levels spike. For that reason, the Keyto founders recommend talking to a doctor if you plan to make any drastic changes to your diet.

The keto diet isn’t for everyone, but any experiment that involves eating healthier and avoiding sugary treats for a while can be worthwhile. I also found motivation to keep going with my own experiment with the Keyto device, which will be available to the general public in late January for $179.